chanserv/batcher/rc4.py

   1 class RC4:
   2   def __init__(self, key, burn=4096):
   3     s = range(256)
   4     for i in xrange(256):
   5       s[i] = i
   6     j = 0
   7     for i in xrange(256):
   8       j = (j + s[i] + ord(key[i % len(key)])) % 256
   9       s[j], s[i] = s[i], s[j]
  10     self.__s = s
  11
  12     if burn:
  13       self.crypt("\x00" * burn)
  14
  15   def crypt(self, data):
  16     ret = []
  17     i = 0
  18     j = 0
  19     for r in xrange(len(data)):
  20       i = (i + 1) % 256
  21       j = (j + self.__s[i]) % 256
  22       self.__s[i], self.__s[j] = self.__s[j], self.__s[i]
  23       ret.append(chr(ord(data[r]) ^ self.__s[(self.__s[i] + self.__s[j]) % 256]))
  24     return "".join(ret)